As a conventional torque sensor, the torque sensor disclosed in JP-A-2002-310819, for example, is known. This torque sensor includes two rings that oppose each other in an axial direction, and is configured such that concavo-convexities are formed on opposing peripheral surfaces of these rings, with these concavo-convexities opposing each other. Between the rings, a magnetic circuit is formed and a Hall element that detects magnetic flux passing through the magnetic circuit is disposed.
When the two rings relatively rotate in response to the size of the applied torsional torque, the state of opposition between the concavo-convexo surfaces of the rings changes, the magnetic resistance therebetween changes, and the output of the Hall element changes. For this reason, the size of the applied torque can be detected from the output of the Hall element.
Patent Document 1: JP-A-2002-310819